Multiplex Integrated Control Unit

Control System DTCs

DTC Troubleshooting: U1280

DTC U1280 : Communication Bus Line Error (BUS-OFF)

NOTE:
* Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors.
* If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.

1. Problem verification:

Problem verification
-1. Clear the DTCs with the HDS.

-2. Turn the ignition switch to LOCK (0) and then back to ON (II).

-3. Wait for at least 6 seconds.

-4. Check for DTCs with the HDS.

Is DTC U1280 indicated?
-YES- Go to step 2.
-NO- Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. B-CAN related units check:

B-CAN related units check
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the appropriate connector at each control unit in the table one at a time. Clear the DTC, then recheck for DTCs after each unit is disconnected.





Is DTC U1280 indicated with each individual unit disconnected?
-YES- Leave the connectors disconnected, and go to step 3.
-NO- Replace the control unit that was disconnected when DTC U1280 did not reset.

3. Shorted wire check (B_CAN lines) 1:

Shorted wire check (B_CAN lines) 1
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connectors.





-3. Check for continuity between test points 1 and 2 individually.














Is there continuity?
-YES- Repair a short to ground in the B_CAN wires.
-NO- Go to step 4.

4. Shorted wire check (B_CAN lines) 2:

Shorted wire check (B_CAN lines) 2
-1. Check for continuity between test points 1 and 2 individually.














Is there continuity?
-YES- Repair a short to ground in the B_CAN wires.
-NO- Go to step 5.

5. Shorted wire check (B_CAN lines) 3:

Shorted wire check (B_CAN lines) 3
-1. Check for continuity between test points 1 and 2 individually.














Is there continuity?
-YES- Repair a short to ground in the B_CAN wires.
-NO- Go to step 6.

6. Shorted wire check (B_CAN-L to B_CAN-H line) 1:

Shorted wire check (B_CAN-L to B_CAN-H line) 1
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the B_CAN wires.
-NO- Go to step 7.

7. Shorted wire check (B_CAN-L to B_CAN-H line) 2:

Shorted wire check (B_CAN-L to B_CAN-H line) 2
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the B_CAN wires.
-NO- Go to step 8.

8. Shorted wire check (B_CAN-L to B_CAN-H line) 3:

Shorted wire check (B_CAN-L to B_CAN-H line) 3
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the B-CAN wires.
-NO- Faulty MICU, replace the under-dash fuse/relay box Service and Repair.